There will be no more 2.x releases (except for bug fixes, of course).
Monger development will focus on 3.0 now. We expect 3.0 to be as compatible
with 2.1 as possible but not 100%: some things (e.g. get-last-error) are gone
in the next release of the Java client or MongoDB 3.0.
We'll post more on our 3.0 plans as they solidify.